Proximity-based applications and services represent a fast growing social and technological trend that may have a major impact on the evolution of cellular wireless/mobile broadband technologies. These services may include the awareness that at least two devices or two users are close to each other and, thus, may be able to directly communicate with each other. Proximity-based applications may include social networking, mobile commerce, advertisement, gaming, etc. Device-to-device (D2D) communication may be seamlessly integrated into current and next generation mobile broadband networks such as 3GPP Long Term Evolution (LTE) and LTE-Advanced. However, the existing mobile broadband networks may not be optimized for D2D specific requirements; for instance, they do not support the establishment of direct links between two devices.
Additionally, small cells using low-power nodes are considered promising to cope with mobile traffic explosion, especially for hotspot deployments in indoor and outdoor scenarios. A low-power node may refer to a node with lower transmit power than a typical macro node (e.g., a macro eNode-B (eNB)). Pico and Femto eNB are representative of low-power nodes.